1. Field of the Invention
The present invention relates to an optoelectrical device, and more specifically to an organic light-emitting display and a method of fabricating the same.
2. Description of the Related Art
According to Snell's law n1*sin θ1=n2*sin θ2 (wherein n1 represents the refractive index of high-refractive materials, n2 represents the refractive index of low-refractive materials, θ1 represents the incident angle of light, θ2 represents the refractive angle of light), the total reflection of light may happen when light is transmitted from higher refractive index material to lower, for example, from glass or dielectric layer to the air. This is because the incident angle (θ1) of some light in the higher refractive index (n1) material is far enough over a critical angle so as to create light having a 90° refractive angle (θ2), wherein some incident light cannot enter the lower refractive index (n2) material.
For an organic light-emitting diode (OLED) featuring self-illumination, some inner light in a pixel cannot be emitted due to the total reflection phenomenon, resulting in light consumption and reduced illumination efficiency. Additionally, when aluminum (Al) is used for a cathode of an OLED, gray level or contrast may be reduced, owing to reflective light from the aluminum and glass plane in the presence of exterior light. Currently, although a polarizer is used to reduce the exterior light effect, it may reduce the inner light transmittance, deteriorating illumination efficiency.
In the related art, an OLED structure is disclosed, for example, in U.S. Pat. No. 6,366,017, and in FIG. 1. Referring to FIG. 1, a substrate 10 is provided. An anode 12, an emissive layer 13, and a transparent conducting layer 14 are formed on the substrate 10 in order. After the emissive layer 13 produces light, some light passes through the transparent conducting layer 14, and other remains, forming total reflection, and resulting in the reduction of light transmittance, and deterioration of element efficiency. To solve this problem, a Distributed Bragg Reflector (DBR) 15 is installed on the transparent conducting layer 14 in the related art to reduce total reflection, increasing element performance to obtain sufficient light source, improving brightness.
Nevertheless, DBR 15 may focus light at specific angles causing the exterior glare, deteriorating the quality of gray level or contrast, and further increasing the process cost.